1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus.
2. Description of the Related Art
The electrophotographic image forming apparatus forms an image on a recording medium using an electrophotographic image forming method. Examples of the electrophotographic image forming apparatus include electrophotographic copying machines, electrophotographic printers (for example, laser beam printers and light-emitting diode (LED) printers), and facsimile apparatuses. Further, a process cartridge is formed by integrating an electrophotographic photosensitive drum and process units that act on the electrophotographic photosensitive drum, into a cartridge to be attachable to and detachable from an image forming apparatus main body. Examples of the process units include charging units, development units, and cleaning units that act on the electrophotographic photosensitive drum.
A development apparatus as the development unit included in the process cartridge mainly includes: a frame member accommodating a developer (hereinafter referred to as “toner”); a development roller placed in an opening portion of the frame member; a supply roller that supplies the toner to the development roller; and a developer regulating member that regulates the thickness of the toner on the development roller.
In the development apparatus having such a configuration, to prevent the toner from flowing out of the opening portion of the frame member, end sealing members (sealing members) are generally provided between respective longitudinal end portions of the development roller and the frame member. The end sealing members are supported being attached to supporting portions of the frame member, and seal the toner by abutting the surface of the development roller in the respective longitudinal end portions thereof. Japanese Patent Application Laid-Open No. 2006-208689 (p. 21, FIGS. 8A and 8B) discusses a method of mounting a supply roller to a frame member by moving the supply roller in an axis direction of the supply roller. In Japanese Patent Application Laid-Open No. 2006-208689 (p. 21, FIGS. 8A and 8B), a through hole is formed on a side surface of the frame member, so that the supply roller is inserted through the through hole in the axis direction of the supply roller, thereby mounting the supply roller to the frame member.
The case is considered where, in the configuration where a through hole is provided to allow the insertion of a supply roller into a frame member accommodating a developer as in the above conventional art, a sealing member is provided between an end portion of a development roller and the frame member. If the sealing member and a supporting portion for supporting the sealing member are located between the development roller and the through hole, the supporting portion may be subjected to the pressure from the development roller through the sealing member and may deform. The deformation of the supporting portion reduces the sealing performance of the sealing member.